Management apparatus, storage system, and storage apparatus management method

ABSTRACT

There is provided a management apparatus of a storage apparatus. The management apparatus includes an acquisition determination section that determines whether predetermined identification information can be acquired or not from a mounting apparatus that mounts at least one storage apparatus and has at least one predetermined identification information assigned thereto, and a failure determination section that determines, based on a determination result of the acquisition determination section, an access failure to the storage apparatus mounted in the mounting apparatus has been caused due to a failure of the storage apparatus itself or an interruption of a power supply to the mounting apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2008-135283, filed on May 23,2008, the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to a storage system capable of storing alarge volume of data, a management apparatus for managing a storageapparatus, and a storage apparatus management method.

BACKGROUND

A storage system provided with a plurality of magnetic disk drives isnow used for storing a huge volume of data.

FIG. 7 is a view schematically illustrating an entire configuration of aconventional storage system. A storage system 300 illustrated in FIG. 7implements a RAID (Redundant Array Independent Disks) configuration fora magnetic disk drive to increase data redundancy so as to providedesirable performance characteristics to a host 200.

A description will be given of functions of respective modulesconstituting the storage system 300. A CA (Channel Adapter) 2 controlsthe interface with the host 200. Upon reception of data write/readoperation request from the host 200, the CA 2 notifies a CM (CentralizedModule) 400 of a processing request. The CA 2 directly accesses a cachememory on the CM 400 to perform data transfer between the storage system300 and host 200.

The CM 400 serves as a core of all the modules constituting the storagesystem 300. The CM 400 performs resource management (manages theresources of each module and executes effective control management).Further, the CM 400 performs cache memory management (manages theallocation of the memory area in the CM 400 and executes generalcontrol). The CM 400 retains maintenance software and uses themaintenance software to provide various services. The CM 400 is providedwith a DI (Device Interface) 11 which is a module for performingcommunication with a DE group 500 (details of which will be describedlater) composed of a plurality of magnetic disk drives. The DI 11 isconnected to the DE group 500 by a fiber channel interface (hereinafter,fiber channel is abbreviated as “FC”). Through the DI 11, the CM 400performs control of the FC interface communicating with the DE group500, I/O control of the magnetic disk drive, control of RAID, and thelike.

For redundancy, the storage system 300 has two CAs 2 and two CMs 400.

FIG. 8 is a view schematically illustrating a multi-initiator connectionbetween the CMs 400 (DI 11) and magnetic disk drives. The DIs 11 andmagnetic disk drives serving as initiators each are provided with an FCport. The respective FC ports are connected to one another to form anarbitrated loop.

Some of the terms used in the following description will be defined.

Arbitrated Loop (Hereinafter, Referred to Merely as “Loop”)

The arbitrated loop is one of fiber channel topologies, in which aplurality of FC ports are connected in a loop so as to allowcommunication to be performed between a pair of the ports. Thearbitrated loop supports up to 127 devices.

AL_PA and Loop ID

An address to be uniquely used in the arbitrated loop is assigned toeach port in the loop. This address is referred to as AL_PA. The valuesof the AL_PA are not consecutive numbers and therefore the AL_PA issometimes difficult to handle. For this reason, consecutive numbers areassigned to the respective AL_PA. Each of the consecutive numbers isreferred to as Loop_ID. The value of the AL_PA can be fixed in a devicein a hardware manner. However, in the case where the same value isassigned to the AL_PA by accident, AL_PA setting in a device nearer to aLoop Master is prioritized according to the priority set in the loop.

Loop Master

The Loop Master is a port that leads loop initialization, which isdetermined at the time of execution of loop initialization. If the loopincludes a fabric port, the fabric port becomes the Loop Master. If theloop does not include a fabric port, a port having the smallest WWN(World Wide Name: world wide unique name) (in the present invention,WWPN (World Wide Port Name is referred to as WWN)) value in the loop isselected as the Loop Master.

Loop Initialization

The loop initialization is a necessary process for recognizing a deviceconnected to the loop so as to make the device operational. The loopinitialization is executed when a LIP (Loop Initialization Primitive) isissued from the Loop Master onto the loop.

Login

The Login is a procedure that exchanges information WWN, etc.) of atarget port before data transfer so as to allow the port to be accessed.

Each FC port carries out the loop initialization when performingcommunication. The AL_PA (identification information) of each FC port isdetermined by the loop initialization. The setting of the AL_PA is madein the connection order of the devices starting from the Loop Master. Avalue to be set to the AL_PA can be specified in a hardware manner (hardassignment), and the specified value is directly set to the AL_PA inmost cases. However, in the case where there exists an AL_PA with a hardassignment value on the loop, the specified AL_PA value is not set butthe AL_PA value is set in a software manner (soft assignment) in thesubsequent sequence in a predetermined order. The order (ascending orderor descending order) of the soft assignment is determined based on apredetermined setting. It goes without saying that the same AL_PA valueas that has been assigned to an FC port by hard assignment is notpermitted.

The login procedure is executed after the loop initialization, and afterthe completion of the login procedure, communication with the magneticdisk drive becomes possible.

FIG. 9 is a view schematically illustrating a relationship between theDEs and magnetic disk drives. An apparatus in which the magnetic diskdrive is mounted is called DE (Drive Enclosure). A plurality of magneticdisk drives can be mounted in one DE. The DE according to the presentinvention can be connected to the arbitrated loop and has a HUB functionthat allows the magnetic disk drive mounted therein to participate inthe loop.

The DE can be connected to the loop by an FCC (Fiber Channel Controller)incorporated therein and can participate in the loop by the AL_PAassigned thereto. By using the DE to constitute a loop and byincorporating the magnetic disk drive in the DE connected to the loop,the magnetic disk drive can easily participate in the loop.

A configuration of the conventional DE group 500 will be described withreference to FIG. 10. The DE group 500 is constituted by a plurality ofDEs 3. The DE 3 is provided with two FCCs 31 which are individuallyconnected to respective magnetic disk drives (Disk 32A, Disk 32B, . . ., Disk 32N, which are sometimes collectively referred to as Disk 32), sothat the two FCCs 31 can refer to the Disk 32 in the same way. With theabove configuration, two access paths can be ensured with respect to therespective disk drives 32. For example, even if one of the two FCCs 31malfunctions to affect one of the two loops in the DE 3, the CM 400 canaccess the Disk 32 using the other side loop. The FCC 31 in one DE 3 iscascade-connected to the FCC 31 in another FCC 31 and thereby theplurality of DEs 3 in the DE group 500 are connected to each other.

A configuration table retained in the CM 400 will be described withreference to FIG. 11. The configuration table is a list for storinginformation concerning the modules constituting the storage system 300and represents a correspondence between the name of a module and statusof the module. When given processing is executed in the storage system300, the content of the configuration table is referred to.

FIG. 12 is a view schematically illustrating I/O processing of thestorage system 300. The CM 400 checks the status of the magnetic diskdrive (Disk 32N) to be accessed by referring to the configuration tablebefore executing I/O processing. When confirming that the magnetic diskdrive to be accessed is in normal status on the configuration table, theCM 400 executes the I/O processing for the magnetic disk drive.

The configuration table is updated every time the status of the modulein the storage system 300 is changed. For example, as illustrated inFIG. 13, in the case where the magnetic disk drive becomes abnormal, thestatus thereof is updated from normal to abnormal.

Configuration table update processing will be described with referenceto FIG. 14. For example, the magnetic disk drive becomes abnormal, theDI 11 notifies the CM 400 of module status change. The CM 400 receivesthe notification of the module status change and then updates the statusof the module on the configuration table. Examples of cases where themodule status is to be changed include a case where the CM 400malfunctions, a case where the DE 3 is removed from a predeterminedposition in the storage system 300, a case where the magnetic disk drivehas failed and cannot be used, a case where a new magnetic disk drive isadded, and the like.

Although, in this manner, the CM 400 updates the configuration tablewhen the module status is changed, there exists a time lag between thetime at which the DI 11 detects the failure of the magnetic disk driveand the time at which the configuration table on the CM 400 is updated.During this time lag, the CM 400 cannot detect the failure of themagnetic disk drive. It follows that the CM 400 cannot inhibit issuanceof I/O but issues I/O even if the magnetic disk drive has failed duringthe time lag.

A further description will be given of the time lag with reference toFIG. 15. Note that the DI 11 retains a different configuration tablefrom that provided in the CM 400, which represents the statuses of themagnetic disk drives. FIG. 15 is a time chart illustrating operations ofthe host 200, CM 400, and DI 11 in the configuration table updateprocessing based on the configuration tables retained in the CM 400 andDI 11. In FIG. 15, the statuses are differentiated by the width of anarrow, and the time flows downward.

In the initial state, all the Disk 32 are in normal status and there isno problem. In the case where the Disk 32N has failed at a given timing,the DI 11 detects the failure of the Disk 32N and updates the status ofthe Disk 32N on the configuration table retained therein from normal toabnormal.

Thereafter, the DI 11 notifies the CM 400 that the DI 11 has updated theconfiguration table retained therein. The CM 400 recognizes that theconfiguration table of the DI 11 has been updated by receiving thenotification from the DI 11 and correspondingly updates theconfiguration table retained in the CM 400. The time lag occurs betweenthe time at which the configuration table retained in the DI 11 isupdated and the time at which the update of the configuration table isnotified to the CM 400, and during this time lag, the CM 400 cannotdetect the abnormality of the Disk 32N.

There is disclosed, as a conventional art, a disk array device capableof preventing any operation leading to the degeneration of theoriginally normal disk device. Further, there is disclosed a controlmethod capable of preventing occurrence of a malfunction in an exchangedhard disk drive (HDD) device and detecting a connection miss of the HDDdevice when an HDD device is exchanged during the operation of a displayarray device.

Further, there is disclosed, as a conventional art, a data storagesystem capable of reducing a load of a data bus for connecting a hostsystem and a data storage system. Further, there is disclosed a RAIDdevice capable of preventing, even in the case where a failure which mayinduce a loop abnormality occurs in a RAID using disks with an FCinterface, correcting the loop abnormality so as to prevent data loss.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2002-108573

Patent Document 2: Japanese Laid-Open Patent Publication No. 11-85412

Patent Document 3: Japanese Laid-Open Patent Publication No. 8-263225

Patent Document 4: Japanese Laid-Open Patent Publication No. 2003-162380

When detecting that access to the magnetic disk drive cannot be made,the storage system 300 provided with conventional DEs 3 determines thatthe magnetic disk drive has failed and logically separates the relevantmagnetic disk drive from the storage system 300. The access disabledstate can be caused by a failure of the magnetic disk drive itself or bypower failure of the DE 3.

When a power failure of the DE 3 occurs, the AL_PA of the magnetic diskdrive provided in the DE 3 disappears from the loop and therefore themagnetic disk drive in the DE 3 becomes invisible to the CM 400. The CM400 records information indicating that the magnetic disk drive in theDE 3 has become invisible to the CM 400 in the configuration table forupdate.

When the information indicating that the magnetic disk drive in the DE 3has become invisible to the CM 400 exists on the configuration table ofthe CM 400, I/O is never executed. However, as described above, a timelag exists until the information of the magnetic disk drive that hasbecome invisible is registered in the configuration table. Thus, atiming at which I/O is issued to the invisible magnetic disk drive mayexist.

FIGS. 16A to 16C and FIGS. 17A to 17C are views illustratingconventional processing executed in the case where I/O is issued, duringthe time lag, to the magnetic disk drive (magnetic disk drive in the DE3 in which a power failure has occurred) provided in the DE 3 which isin a disabled state due to occurrence of a power failure. In FIGS. 16Ato 16C and FIGS. 17A to 17C, A and B each denote a loop. That is, thestorage system 300 has two paths to the DE 3.

FIG. 16A illustrates a normal state, and FIG. 16B illustrates a statewhere a power failure has occurred in the DE 3. When a power failureoccurs in the DE 3, the AL_PA of the magnetic disk drive provided in theDE 3 and therefore the magnetic disk drive temporarily disappears(during the power failure) from the loop. The reason that the AL_PAdisappears is that loop initialization is activated in the case where apower failure has occurred in the DE 3 and, in this case, the value ofthe AL_PA is not determined.

When an access request to the magnetic disk drive is generated in thisstate, the CM 400 tries to access the magnetic disk drive of the DE 3 inwhich a power failure has occurred through one path (in this case, pathA), but the access fails (see FIG. 16C).

The CM 400 then tries to access the magnetic disk drive through theother path (in this case, path B), but the access fails (see FIG. 17A).The CM 400 recognizes that the access operation to the magnetic diskdrive using all the access paths has failed and determines that themagnetic disk drive to be accessed has failed. At this timing, the CM400 logically separates the magnetic disk drive from the storage system300.

When a power supply is resumed to the DE 3, the DE 3 is recovered. Atthis time, the AL_PA of the magnetic disk drive provided in the DE 3appears and, therefore, the magnetic disk drive has become visible onthe loop (see FIG. 17B).

When the DE 3 is recovered after the resumption of power supply, themagnetic disk drive is accordingly recovered. However, the magnetic diskdrive that was determined to be abnormal earlier is still separated fromthe storage system 300 as one in an access disabled state (see FIG.17C). As described above, since the power failure of the DE 3 cannot bedetected, the CM 400 has no choice but to determine that thedisappearance of the magnetic disk drive in the DE 3 from the loop iscaused by a failure of the magnetic disk drive even in the case where apower failure has actually occurred in the DE 3.

When it has been once determined that the magnetic disk drive has failedas described above, magnetic disk drive is still recognized as failedone even after the resumption of power supply. In order to recover thestorage system 300 to a normal state afterward, it is necessary toreplace the magnetic disk drive that has been determined to have failedalthough the magnetic disk drive is actually normal.

A further description will be given of the above processing withreference to the flowchart of FIG. 18.

A power failure of the DE 3 occurs and the AL_PA of the magnetic diskdrive in the DE 3 in which the power failure has occurred disappearsfrom the loop (step S101). The storage system 300 cannot detect thepower failure.

In the case where an I/O access has been issued to the magnetic diskdrive (step S102), the CM 400 uses a first access path to determinewhether the AL_PA of the access target magnetic disk drive exists on theloop (step S103: first determination).

In the case where the AL_PA of the access target magnetic disk drivedoes not exist on the loop (No in step S103), the I/O processing for themagnetic disk drive fails. The CM 400 then uses a second access path todetermine whether the AL_PA of the access target magnetic disk driveexists on the loop (step S104: second determination).

In the case where the existence of the AL_PA of the access targetmagnetic disk drive cannot be detected also in the second determination(No in step S105), which means the magnetic disk drive does not exist onthe loop on both paths, so the CM 400 determines that an abnormality hasoccurred in the magnetic disk drive and updates the configuration tableretained therein. It should be noted that the CM 400 updates the statusof the magnetic disk drive on the configuration table from normal toabnormal and determines that the failure of the I/O processing for themagnetic disk drive is due to a failure in the magnetic disk drive.

In the case where the existence of the AL_PA of the access targetmagnetic disk drive can be detected in the first determination (Yes instep S103), which means that the access target magnetic disk drive is amagnetic disk drive unrelated to the power failure of the DE 3, so theI/O processing is performed without problems. Further, in the case wherethe existence of the AL_PA of the access target magnetic disk drive canbe detected in the second determination (Yes in step S105), the CM 400uses the second access path to perform the I/O processing for themagnetic disk drive without problems (step S107).

Considering the above, the following problems exist in the conventionalstorage system 300.

The storage system 300 cannot detect the power failure of the DE 3, sothat when the power failure occurs in the DE 3, the storage system 300recognizes as if the magnetic disk drive provided in the DE 3 suddenlydisappeared from the loop and, as a result, determines that a failurehas occurred in the magnetic disk drive.

Further, in the case where I/O processing is executed, during the timelag, for the magnetic disk drive in the DE 3 in which a power failurehas occurred, the I/O processing fails. Further, since the magnetic diskdrive does not exist on the loop, the CM 400 determines that any failurehas occurred in the magnetic disk drive and separates the magnetic diskdrive from the storage system 300. After the DE 3 is recovered from thepower failure, the magnetic disk drive, which has not actually failed,appears on the loop. However, since the magnetic disk drive isdetermined to have failed at the time of occurrence of the powerfailure, it is not incorporated in the storage system 300, treated as afailed one, and forced to be replaced with a new one.

SUMMARY

According to an aspect of the present invention, there is provided amanagement apparatus of a storage apparatus, the management apparatusincluding an acquisition determination section that determines whetherpredetermined identification information can be acquired or not from amounting apparatus that mounts at least one storage apparatus and has atleast one predetermined identification information assigned thereto, anda failure determination section that determines, based on adetermination result of the acquisition determination section, an accessfailure to the storage apparatus mounted in the mounting apparatus hasbeen caused due to a failure of the storage apparatus itself or aninterruption of a power supply to the mounting apparatus.

According to another aspect of the present invention, there is provideda storage system including a mounting apparatus that mounts at least onestorage apparatus and has at least one predetermined identificationinformation assigned thereto; an acquisition determination section thatdetermines whether the predetermined identification information can beacquired or not from the mounting apparatus and a failure determinationsection that determines, based on a determination result of theacquisition determination section, an access failure to the storageapparatus mounted in the mounting apparatus has been caused due to afailure of the storage apparatus itself or an interruption of a powersupply to the mounting apparatus.

According to another aspect of the present invention, there is provideda storage apparatus management method including determining whetherpredetermined identification information can be acquired or not from amounting apparatus that mounts at least one storage apparatus and has atleast one predetermined identification information assigned thereto; anddetermining, based on a result of the acquisition determination, anaccess failure to the storage apparatus mounted in the mountingapparatus has been caused due to a failure of the storage apparatusitself or an interruption of a power supply to the mounting apparatus.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example of a configuration ofa storage system according to an embodiment of the present invention;

FIGS. 2A to 2C are views illustrating an example of processing executedin the storage system according to the present embodiment;

FIGS. 3A to 3C are views illustrating an example of processing executedin the storage system according to the present embodiment;

FIGS. 4A and 4B are views illustrating an example of processing executedin the storage system according to the present embodiment;

FIG. 5 is a flowchart illustrating an example of a processing procedureexecuted in the storage system according to the present embodiment;

FIG. 6 is a flowchart illustrating an example of a processing procedureexecuted in the storage system according to the present embodiment;

FIG. 7 is a view schematically illustrating a configuration of aconventional storage system;

FIG. 8 is a view schematically illustrating a connection between DEs(DIs) and magnetic disk drives;

FIG. 9 is a view schematically illustrating a relationship between DEsand magnetic disk drives;

FIG. 10 is a block diagram illustrating an example of a configuration ofa DE group;

FIG. 11 is a view illustrating a configuration table retained in a CM;

FIG. 12 is a view schematically illustrating I/O processing of thestorage system;

FIG. 13 is a view illustrating update (from normal to abnormal) of theconfiguration table;

FIG. 14 is a view schematically illustrating configuration table updateprocessing;

FIG. 15 is a view illustrating a time lag occurring in the configurationtable update processing;

FIGS. 16A to 16C are views schematically illustrating processingexecuted in the case where a power failure has occurred in aconventional DE;

FIGS. 17A to 17C are views schematically illustrating processingexecuted in the case where a power failure has occurred in aconventional DE; and

FIG. 18 is a flowchart illustrating processing executed in theconventional storage system.

DESCRIPTION OF EMBODIMENT(S)

FIG. 1 illustrates an example of a storage system according to anembodiment of the present invention.

A storage system 100 of FIG. 1 is provided with CAs 2, CMs 1, and a DEgroup 500. The CM 1 additionally includes an acquisition determinationsection 12 and a failure determination section 13 as compared to theconventional CM 400. The internal configurations of the CA 2 and DEgroup 500 are the same as those in the conventional storage system 300and the descriptions thereof are omitted here (see configuration viewsof FIGS. 7 and 10).

The acquisition determination section 12 determines whether AL_PA(predetermined identification information) assigned to the DE 3 providedwith at least one magnetic disk drive (storage apparatus) can beacquired or not. The AL_PA assigned to the DE 3 concretely means theAL_PA assigned to the FCC 31 provided in the DE 3.

The failure determination section 13 determines, based on adetermination result of the acquisition determination section 12,whether an access disabled state of the magnetic disk drive provided inthe DE 3 is caused by a failure of the magnetic disk drive itself or aninterruption of power supply to the DE 3.

The functions of the acquisition determination section 12 and failuredetermination section 13 are realized by cooperation of softwareretained in a not illustrated non-volatile memory in the CM 1 and notillustrated hardware resources, such as a CPU or memory, provided in theCM 1.

The general operation of the present embodiment will be described below.In the case where the AL_PA of the magnetic disk apparatus does notexist on all the access paths although the loop is normal in a statewhere the storage system 100 issues an I/O instruction to the magneticdisk drive, the storage system 100 checks whether the DE 3 incorporatingthe magnetic disk drive exists on the storage system 100. In the presentembodiment, confirmation of the existence of the DE 3 is made bydetermining whether the AL_PA assigned to the FCC 31 provided in the DE3 exists on the loop.

In the case where the DE 3 has disappeared from the loop, the storagesystem 100 determines that the power failure of the DE 3 has caused thedisappearance of the access paths to the magnetic disk drive and thatthe magnetic disk drive is normal. The reason that such determinationcan be made is as follows. That is, if the disappearance is caused dueto a failure of the magnetic disk drive itself, it can be expected thatonly the AL_PA of the magnetic disk drive cannot be confirmed on theloop but the AL_PA of the FCC 31 can be confirmed. On the other hand, ifthe disappearance is caused due to the power failure of the DE 3, boththe AL_PAs assigned to the magnetic disk drive and FCC 31 can disappearfrom the loop. As a result, in the case where both the AL_PAs of themagnetic disk drive and FCC 31 do not exist on the loop, it is possibleto determine that the disappearance is caused due to the power failure.

In the case where an I/O instruction is issued from the host 200 to aninvisible magnetic disk drive during the time lag associated with theupdate of the configuration table, there is no problem if the powerfailure can be detected during the I/O processing. Further, after therecovery of the power failure, the AL_PAs of the DE 3 and magnetic diskdrive appear on the loop, resulting in the recovery of normal statebefore occurrence of the power failure. Thus, unlike the conventionalstorage system, it is possible to use the magnetic disk drive after therecovery of the DE 3 even if an access is made to the magnetic diskdrive during the power failure.

The processing of the storage system 100 is illustrated in FIGS. 2A to2C, 3A to 3C, and 4A and 4B.

The series of processing from FIG. 2A to FIG. 2C are the same as thoseillustrated in FIG. 16A to FIG. 16C, and the descriptions thereof areomitted here.

Although the CM 1 tries to access (access retry) the magnetic disk driveusing a path (in this case, path B) different from a path through whichan access has failed, this access also fails (see FIG. 3A). The failuredetermination section 13 recognizes that accesses to the magnetic diskdrive through all the paths have failed and determines, at this stage,that the magnetic disk drive has failed.

After the accesses through both the paths (path A and path B) havefailed by the processing up to FIG. 3A, the acquisition determinationsection 12 checks whether the FCC 31 of the DE 3 in which the magneticdisk drive to which the access is disabled is provided exists or not(see FIG. 3B). In this case, the acquisition determination section 12confirms the existence of the FCC 31 by determining whether the AL_PAassigned to the FCC 31 can be acquired or not. When confirming that theFCC 31 does not exist, the failure determination section 13 cancels thedetermination of FIG. 3A, indicating that the magnetic disk drive hasfailed and newly determines that the access disable state is caused dueto the power failure of the DE 3 (see FIG. 3C).

It should be noted that the acquisition determination section 12performs the above confirmation of existence of the FCC 31 for all theaccess paths (in the present embodiment, path A and path B). This isbecause that when the confirmation is performed for only one path, it isimpossible to determine whether the access disabled state is due to afailure of the FCC itself on the one path or due to a power failure ofthe DE 3.

When a power supply is resumed to the DE 3, the DE 3 is recovered. Atthis time, the AL_PA of the magnetic disk drive provided in the DE 3appears and, therefore, the magnetic disk drive has become visible onthe loop (see FIG. 4A). As described above, the magnetic disk drive towhich an access has been made during the power failure appears on theloop. That is, even if an_access has been made to the magnetic diskdrive during the power failure, the magnetic disk drive is not separatedfrom the storage system 100 but can be used in the same way as beforethe occurrence of the power failure (see FIG. 4B).

A processing procedure executed in the storage system 100 according tothe present embodiment will be described with reference to theflowcharts of FIGS. 5 and 6.

The processing from step S1 to step S5 (occurrence of the power failureof the DE 3 through one path (step S1), issuance of I/O to the magneticdisk drive (step S2), determination on whether the magnetic disk driveexists on the loop through the one path (step S3), issuance of I/Othrough the other path (step S4), determination on whether the magneticdisk drive exists on the loop through the other path (step S5)) are thesame as the processing from step S101 to step S105 illustrated in FIG.18, and the descriptions thereof are omitted here (see FIG. 18).

When the determination results in steps S3 and S5 reveal that existenceof the magnetic disk drive cannot be detected through both the paths (Noin step S5), which means that the occurrence of the power failure issuspected, so the power failure check processing for the DE 3 (performedby the acquisition determination section 12) is started (step S8).

The acquisition determination section 12 checks whether the FCC 31 ofthe DE 3 in which the access target magnetic disk drive is providedexists on the loop by determining whether the AL_PA of the FCC 31 can beacquired or not (step S9). In the case where the AL_PA of the FCC 31cannot be acquired and therefore the disappearance of the FCC 31 isconfirmed (No in step S10), the failure determination section 13determines that a power failure has occurred in the DE 3 since the FCC31 of the DE 3 does not exist on the loop (step S11). At this time, theCM 1 determines that the access disabled state is caused due to thepower failure of the DE 3 and treats the magnetic disk drive itself asnormal. For example, the CM 1 updates the status of the magnetic diskdrive on the configuration table (see FIGS. 11 and 13) provided thereinto a status different from the abnormal status (for example, to a flagindicating a power failure status) and continues the I/O processingaccording to the power failure status.

On the other hand, in the case where the AL_PA of the FCC 31 can beacquired and therefore the existence of the FCC 31 is confirmed (Yes instep S10), the failure determination section 13 determines that afailure has occurred in the magnetic disk drive since only the magneticdisk drive has disappeared from the loop (step S12). At this time, theCM 1 determines that the access disabled state is caused due to thefailure of the magnetic disk drive itself, updates the status of themagnetic disk drive on the configuration table (see FIGS. 11 and 13)provided therein to abnormal status, and continues the I/O processingaccording to the abnormal status of the magnetic disk drive.

In the case where a result of the processing of step S3 or step S5 isYes, the I/O processing is normally performed (steps S6 or S7).

A mounting apparatus corresponding to the DE 3 including the FCC 31 inthe present embodiment, identification information corresponds to theAL_PA in the present embodiment. Predetermined identificationinformation corresponds to the AL_PA assigned to the FCC 31 in thepresent embodiment. A management apparatus corresponds to the CM 1 inthe present embodiment. Access processing refers to a series ofprocessing steps from the issuance of the I/O request to the magneticdisk drive by the host 200 to data read/write operation from/onto themagnetic disk drive (regardless of whether the read/write operationsucceeds or fails).

By adopting the method according to the present embodiment, even astorage system provided with a DE that does not have a power failuredetection function can detect the occurrence of a power failure andprevents a failure of the magnetic disk drive from being erroneouslydetected.

Further, by adopting the method according to the present embodiment, itis possible to detect the power failure of the DE during the I/Oprocessing, thereby determining a cause of the disappearance of theAL_PA of the magnetic disk drive without waiting completion of updateprocessing of apparatus configuration.

Whether an access failure to the storage apparatus is due to a failureof the storage apparatus itself or due to an interruption of a powersupply to the mounting apparatus can be determined. Thus, it is possibleto prevent a failure of the storage apparatus from being erroneouslydetected, thereby preventing unnecessary replacement of the storageapparatus.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiment(s) of the presentinventions have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

1. A management apparatus of a storage apparatus, comprising: anacquisition determination section that determines whether predeterminedidentification information can be acquired or not from a mountingapparatus that mounts at least one storage apparatus and has at leastone predetermined identification information assigned thereto; and afailure determination section that determines, based on a determinationresult of the acquisition determination section, an access failure tothe storage apparatus mounted in the mounting apparatus has been causeddue to a failure of the storage apparatus itself or an interruption of apower supply to the mounting apparatus.
 2. The management apparatusaccording to claim 1, wherein in the case where the determination resultof the acquisition determination section is negative, the failuredetermination section determines that the access failure is due to thepower supply interruption to the mounting apparatus.
 3. The managementapparatus according to claim 1, wherein the determination processingmade by the acquisition determination section and determinationprocessing made by the failure determination section are performedduring access processing to the storage apparatus.
 4. The managementapparatus according to claim 1, wherein the storage apparatus andmounting apparatus are connected to each other in an arbitrated looptopology.
 5. The management apparatus according to claim 4, whereinidentification information are assigned to apparatuses that areparticipating in the arbitrated loop, and the predeterminedidentification information is assigned to the mounting apparatus.
 6. Themanagement apparatus according to claim 1, wherein in the case whereplurality of the predetermined identification information are assignedto the mounting apparatus, the acquisition determination sectiondetermines all the predetermined identification information can beacquired or not.
 7. A storage system, comprising: a mounting apparatusthat mounts at least one storage apparatus and has at least onepredetermined identification information assigned thereto; anacquisition determination section that determines whether thepredetermined identification information can be acquired or not from themounting apparatus; and a failure determination section that determines,based on a determination result of the acquisition determinationsection, an access failure to the storage apparatus mounted in themounting apparatus has been caused due to a failure of the storageapparatus itself or an interruption of a power supply to the mountingapparatus.
 8. The storage system according to claim 7, wherein in thecase where the determination result of the acquisition determinationsection is negative, the failure determination section determines thatthe access failure is due to the power supply interruption to themounting apparatus.
 9. The storage system according to claim 8, whereinthe determination processing made by the acquisition determinationsection and determination processing made by the failure determinationsection are performed during access processing to the storage apparatus.10. The storage system according to claim 7, wherein the storageapparatus and mounting apparatus are connected to each other in anarbitrated loop topology.
 11. The storage system according to claim 10,wherein identification information are assigned to apparatuses that areparticipating in the arbitrated loop, and the predeterminedidentification information is assigned to the mounting apparatus. 12.The storage system according to claim 7, wherein in the case whereplurality of the predetermined identification information are assignedto the mounting apparatus, the acquisition determination sectiondetermines all the predetermined identification information can beacquired or not.
 13. A storage apparatus management method, comprising:determining whether predetermined identification information can beacquired or not from a mounting apparatus that mounts at least onestorage apparatus and has at least one predetermined identificationinformation assigned thereto; and determining, based on a result of theacquisition determination, an access failure to the storage apparatusmounted in the mounting apparatus has been caused due to a failure ofthe storage apparatus itself or an interruption of a power supply to themounting apparatus.
 14. The storage apparatus management methodaccording to claim 13, wherein in the case where the result of theacquisition determination is negative, it is determined that the accessfailure is due to the power supply interruption to the mountingapparatus, in the failure determination.
 15. The storage apparatusmanagement method according to claim 13, wherein the acquisitiondetermination and failure determination are executed by a computer thatcontrols an access to the storage apparatus, and the acquisitiondetermination and the failure determination are performed during theaccess processing to the storage apparatus.
 16. The storage apparatusmanagement method according to claim 13, wherein the storage apparatusand mounting apparatus are connected to each other in an arbitrated looptopology.
 17. The storage apparatus management method according to claim16, wherein identification information are assigned to apparatuses thatare participating in the arbitrated loop, and the predeterminedidentification information is assigned to the mounting apparatus. 18.The storage apparatus management method according to claim 13, whereinin the case where plurality of the predetermined identificationinformation are assigned to the mounting apparatus, it is determinedwhether or not all the predetermined identification information can beacquired, in the acquisition determination.